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* Replace all old-style classes. [[#a 4]] | |
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* Remove support for old-style classes--all classes will be new-style. [[#a 4]] * Remove {{{`x`}}} in favor of `repr(x)`. [[#a 1]] * Remove the `lambda` statement. [[#a 1]] [[#a 4]] * Remove support for string exceptions. [[#a 1]] |
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* Do something so you can catch multiple exceptions using 'except E1, E2, E3:'. Maybe use 'except E1, E2, E3 as err:' if you want the error variable? (added by GvR, suggested by Bram Cohen). | * Do something so you can catch multiple exceptions using `except E1, E2, E3:`. Perhaps use `except E1, E2, E3 as err:` if you want the error variable. (Added by GvR, suggested by Bram Cohen.) |
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* Remove {{{`x`}}}. [[#a 1]] Alternatively: use `repr(x)`. Reasoning: backticks are hard to read in many fonts and can be mangled by typesetting software. * Remove the `lambda` statement. [[#a 1]] [[#a 4]] Alternatively: use a local function. Reasoning: `lambda` supports only one statement. * Remove support for string exceptions. [[#a 1]] Alternatively: use a class. |
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* Remove `dict.iteritems()`, `dict.iterkeys()`, `dict.itervalues()`. | * Move `compile()`, `intern()` and `id()` to the `sys` module. [[#a 1]] |
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* Remove `apply()`. Use `f(*args, **kw)` instead. [[#a 1]] * Remove `xrange()`. Use `range()` instead. [[#a 1]] [[#a 4]] * Remove `map()` and `filter()`. Use list comprehensions instead. [[#a 1]] [[#a 4]] |
* Remove `dict.iteritems()`, `dict.iterkeys()`, and `dict.itervalues()`. Alternatively: use `dict.items()`, `dict.keys()`, and `dict.values()` respectively. * Remove `apply()`. [[#a 1]] Alternatively: use `f(*args, **kw)`. * Remove `xrange()`. [[#a 1]] [[#a 4]] Alternatively: use `range()`. * Remove `map()` and `filter()`. [[#a 1]] [[#a 4]] Alternatively: use list comprehensions. |
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* Remove `reduce()`. Use a loop instead. [[#a 1]] * Remove `callable()`. Catch the exception instead. [[#a 1]] * Remove `buffer()` in favor of a new `bytes` type. [[#a 1]] [[#a 2]] * Remove `raw_input()`. Use `sys.stdin.readline()` instead. [[#a 1]] * Remove `input()`. Use 'eval(sys.stdin.readline())` instead. [[#a 1]] * Remove `execfile()` and `reload()`. Use `exec()` instead. [[#a 1]] * Move `compile()`, `intern()` and `id()` to the `sys` module. [[#a 1]] |
* Remove `reduce()`. [[#a 1]] Alternatively: use a loop. * Remove `callable()`. [[#a 1]] Alternatively: catch the exception. * Remove `buffer()`. [[#a 1]] [[#a 2]] Alternatively: use new `bytes` type. * Remove `raw_input()`. [[#a 1]] Alternatively: use `sys.stdin.readline()`. * Remove `input()`. [[#a 1]] Alternatively: use `eval(sys.stdin.readline())`. * Remove `execfile()` and `reload()`. [[#a 1]] Alternatively: use `exec()`. |
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* Remove `string` and other deprecated modules. [[#c 3]] [[#a 4]] * Remove `sys.exc_type` as it is not type safe. Use `sys.exc_info` instead. [[#a 1]] |
* Remove `string` module. [[#c 4]] Alternatively: use string methods. * Remove other deprecated modules. [[#c 3]] * Remove `sys.exc_type`. [[#a 1]] Alternatively: use `sys.exc_info`. Reason: as it is not thread safe. |
This page lists features that GvR has mentioned as goals for Python 3.0.
(Another list is at PythonThreeDotOh, but it incorporates items that GvR has never talked about.)
Core Language Changes
Remove distinction between int and long types. #a 4
Make all strings unicode, and have a separate bytes type. #a 2 #a 4
Replace all old-style classes. #a 4
Make the exec statement a function (again.) #a 1
Make the print statement a function. (write(x,y,z), writeln(x,y,z)) #a 1
- Perhaps have optional declarations for static typing.
Do something so you can catch multiple exceptions using except E1, E2, E3:. Perhaps use except E1, E2, E3 as err: if you want the error variable. (Added by GvR, suggested by Bram Cohen.)
Add a with statement:
with self: .foo = [1, 2, 3] .bar(4, .foo)
Remove `x`. #a 1
Alternatively: use repr(x). Reasoning: backticks are hard to read in many fonts and can be mangled by typesetting software.
Remove the lambda statement. #a 1 #a 4
- Alternatively: use a local function.
Reasoning: lambda supports only one statement.
- Alternatively: use a local function.
Remove support for string exceptions. #a 1
- Alternatively: use a class.
Built-In Changes
Have range(), zip(), dict.keys(), dict.items(), and dict.values() return iterators.
Move compile(), intern() and id() to the sys module. #a 1
Change max() and min() to consume iterators.
Remove dict.iteritems(), dict.iterkeys(), and dict.itervalues().
Alternatively: use dict.items(), dict.keys(), and dict.values() respectively.
Remove apply(). #a 1
Alternatively: use f(*args, **kw).
Alternatively: use range().
Remove map() and filter(). #a 1 #a 4
- Alternatively: use list comprehensions.
Remove coerce() as it is obsolete. #a 1
Remove reduce(). #a 1
- Alternatively: use a loop.
Remove callable(). #a 1
- Alternatively: catch the exception.
Alternatively: use new bytes type.
Remove raw_input(). #a 1
Alternatively: use sys.stdin.readline().
Remove input(). #a 1
Alternatively: use eval(sys.stdin.readline()).
Remove execfile() and reload(). #a 1
Alternatively: use exec().
Standard Library Changes
Remove string module. #c 4
- Alternatively: use string methods.
Remove other deprecated modules. #c 3
Remove sys.exc_type. #a 1
Alternatively: use sys.exc_info. Reason: as it is not thread safe.
Unresolved Issues
L += x and L.extend(x) are equivalent.
Can the order of parameter of the insert method be changed so the the index parameter is optional and list.append can be removed?
What is the status of the <> operator?
References
Anchor(a) [1] Python Regrets: http://www.python.org/doc/essays/ppt/regrets/PythonRegrets.pdf
Anchor(b) [2] PEP 296 -- Adding a bytes Object Type: http://python.org/peps/pep-0296.html
Anchor(c) [3] PEP 4 -- Deprecation of Standard Modules: http://python.org/peps/pep-0004.html
Anchor(d) [4] PyCon 2003 State of the Union Address: http://www.python.org/doc/essays/ppt/pycon2003/pycon2003.ppt